1. Field of the Invention
The present invention relates to an image processing method and image processing apparatus for converting the resolution of an image, and a non-transitory computer-readable medium.
2. Description of the Related Art
For image processing apparatuses such as a printer and MFP (Multi Function Peripheral), there is proposed an arrangement in which a high-resolution image signal is converted into low-resolution image data to output an image at a high definition. For example, there is proposed an arrangement in which a low-resolution printer outputs each pixel of high-resolution bitmap data by using a spot multiplexing technique (see Japanese Patent Laid-Open No. 04-336859). This technique has a feature in which, for example, even a 600-dpi printer can express an image quality equivalent to 1,200 dpi.
There is also proposed an arrangement in which the resolution of a portion where high-resolution data needs to be rasterized in a controller is converted into low-resolution data to suppress the loads on a printer and controller and obtain a high-definition image quality (see Japanese Patent Laid-Open No. 2004-201283). In this case, the first image data having the first resolution N is converted into the second image data having the second resolution M lower than the first resolution, and the second image data is output.
In the above-mentioned arrangement, when performing resolution conversion from the first image data having the first resolution N into the second image data having the second resolution M, the resolution conversion ratio N/M needs to be an integral multiple. For example, assume that the resolution N is 1,200 dpi, and the resolution M is 600 dpi. In this case, the resolution conversion ratio N/M is 1200/600=2, which is an integral multiple.